Thursday, December 31, 2009

Currently, photovoltaic collectors are made of 6 inch square solar bricks. Nielson and his team have found a way to make tiny solar cells only 14 to 20 micrometers thick and 0.25 to 1 millimeter across. To put that in perspective, a human hair is somewhere around 100 micrometer thick. It’s no wonder the tiny cells have been referred to as ‘glitter’! And like glitter, these tiny cells could be incorporated into clothing, or made part of any number of objects.

In addition, the engineers expect the new solar cells to be significantly cheaper to make and install. With intelligent controls designed into them, they could forever change the way we maintain our houses and warehouses.

So, with that optimistic thought, and to borrow a turn of phrase from the late great Isaac Asimov, I wish all my gentle readers a happy New Year.

You’ve all seen those ubiquitous wavy, squashy words that have to be typed into boxes before you can sign onto websites. Those oddly shaped words, called ‘captcha’ (Completely Automated Public Turing test to tell Computers and Humans Apart), were developed as a way to thwart computer robots. Although very difficult for computers to decipher, the words are not usually a problem for people. They’ve been used as security measures since the late 90’s.

Turing tests, named for Alan Turing, a WWII mathematician who broke the Nazi Enigma code machine, are designed to distinguish humans from computers. A computer that can fool a human being in a natural language conversation into thinking it is another human is said to have passed the test. To date, no computer has done such a thing.

On the other hand, computers are able to spam email, send automated posts to blogs or forums, and otherwise wreak havoc. Captcha was designed to prevent this sort of mayhem by locking out non-human responders.

Unfortunately, as spammers learn new ways to get around these roadblocks, security measures must be constantly updated.

Danny Cohen-Or of Tel Aviv University found a novel way of impeding computer hackers. He and his colleagues created ‘emergent images’, images that could only be interpreted by watching them move. For example, an image might blend into the background until it moved. At that point, humans can recognize it, but computers still can’t.

Rather than deciphering a wavy word and typing it into a box, captcha in the future might consist of a brief video and then a multiple choice question about what was seen.

This sort of effect has been seen before. Calorie restriction can decrease aging in a variety of organisms ranging from nematodes to monkeys. One of the prominent theories is that calorie restriction works by decreasing insulin levels. Other theories involve reduced numbers of cell divisions, lower metabolism rates or decreased (or increased) levels of free radicals.

This time, the researchers examined human cells grown in culture. They provided human lung cells with either normal or reduced levels of glucose. When fed on reduced levels of glucose, the cells lived longer. The scientists next examined gene expression in the cells. They discovered that compared with cells fed normal amounts of glucose, the deprived cells had elevated telomerase activity and decreased p16 activity.

Before dividing, cells must first replicate their DNA. Because of the nature of DNA replication, the very ends of the DNA strands cannot be copied. In order to prevent the loss of necessary genetic information, the ends of DNA strands contain long repeats of non-coding nucleotides called telomeres. The telomeres form a discardable buffer zone. With each successive replication, some of that buffer is lost, until the genetic information itself is at risk. At that point, the cell can no longer divide and it dies.

Drawing of a telomere at the end of a chromosome

Telomerase is an enzyme which adds to the length of the telomeres. This increases the number of doublings a cell can undergo, and thereby increases the effective lifespan of the cell.

Interestingly, when the same conditions were applied to precancerous human lung cells, the cells showed opposite effects, with decreased levels of telomerase and increased levels of p16. Thus, not only did the calorie restriction increase the lifespan of normal cells, it also preferentially killed cancerous cells.

Calorie restriction has never been shown to be effective in humans, and even this study only looked at cells in culture, not actual human beings. Still, the results give one pause, and if nothing else, might be useful for treating cancer or other diseases.

Tuesday, December 29, 2009

Researchers from Hebrew University have uncovered evidence of modern human cultural traits dated to 750,000 years ago.That’s three times older than previously estimated.

Under the direction of Naama Goren-Inbar, the Gesher Benot Ya'aqov site in northern Israel was excavated.Archeologists found not only extensive evidence of hearth and tool use, but also a division of living space into separate usage areas. That sort of compartmentalization is a hallmark of modern humans.

The two distinct areas that were uncovered include one that was primarily used for flint knapping and for processing fish, and a second that appears to have been put to more general usage.A variety of stone tools were found in the second area, including hand axes, awls, scrapers and chopping tools, some of which had clearly been used for processing nuts. Wood fuel was also found in the second area.

The level of organization and communication required for this division of labor and space had previously only been dated to 250,000 years ago. The 750,000 year old layer excavated at Gesher Benot Ya'aqov pushes back the origin of that complex behavior by half a million years.

Monday, December 28, 2009

The fossil whale, Mammalodon colliveri, was actually discovered in 1932 in southeastern Australia, but was not studied until recently. Erich Fitzgerald found that it lived 25 to 28 million years ago and was about nine feet long. Its mouth features suggest that it made its living by suction feeding, vacuuming prey from muddy ocean bottoms.

It had the jaw and skull structures distinctive of today's baleen whales, but unlike modern baleens, it also had teeth. Modern baleen whales use fibrous structures called baleen to filter tiny prey called krill from seawater. In contrast, modern toothed whales capture larger prey such as fish or other marine mammals.

Mammalodon colliveri used its mouth structures to suck prey up from the bottom, filtering the prey from the mud. It then had teeth it could employ to eat larger items. This suggests that baleen whales may have evolved from toothed whales that relied more and more on the sucking and filtering aspects of feeding, and less on the need for teeth.

‘Blue stragglers’ are stars that seem to violate the normal star life cycle of running out of fuel as they mature. At an age when they should be out of fuel, they are as hot and bright as younger stars.

After a decade of observation, Robert Mathieu of the University of Wisconsin-Madison has outlined three possible scenarios for creating blue stragglers.

If a star is part of a binary pair with a red giant, the red giant can lose its outer envelope to that companion star, turning it into a blue straggler.

Blue stragglers can form as a result of stellar collisions. Although single stars have little chance of colliding, stars in binary or larger systems can hit each other as the clusters cross paths.

A third star entering a binary system can cause the pair of stars to fuse into one blue straggler.

Mathieu studied the star cluster NGC 188 using the WIYN Telescope on Kitt Peak, Arizona. NGC 188 contains several thousand stars of uniform age and at least 21 blue stragglers. It even contains one binary pair of two blue stragglers. They were probably created independently as part of separate pairs, and then ejected their old partners to join up with each other.

Chimps have been observed fashioning spears by breaking off branches, trimming them of extras twigs and leaves and bark, and even sharpening the ends with their teeth. These spears are thrust into crevices to extract game.

Now, chimps have been observed chopping up food using hammers and anvils. The food in question is the fruit of the Treculia africanatree. Although not covered with a hard shell, the fruits themselves are hard and fibrous, and too large for the chimps to bite into. Chimps have managed to get around this problem by using stone or wooden cleavers to chop the fruits into manageable portions. This behavior is distinct from the process of smashing nuts open.

This ability, like all primate tool use, is clearly cultural as it is not shared by chimps in neighboring areas.

A team of scientists led by Igor Aronson at the U.S. Department of Energy's (DOE) Argonne National Laboratoryplaced Bacillus subtilisbacteria in a solution containing microgears which were a million times larger than the bacteria. The microgears, manufactured in collaboration with Northwestern University, contained slanted spokes. Although bacteria normally swim randomly through solution, when enough of them collide with the spokes, the gears begin turning. When two gears are connected, the bacteria spin the gears together.

Like all obligate aerobic organisms, Bacillus subtilis requires oxygen in order to function. The less oxygen, the slower they go. If you remove all oxygen, they completely stop moving, but they can be revived by adding back oxygen. In this way, the speed of gear turning can be carefully controlled.

"Our discovery demonstrates how microscopic swimming agents, such as bacteria or man-made nanorobots, in combination with hard materials can constitute a 'smart material' which can dynamically alter its microstructures, repair damage, or power microdevices."

Thursday, December 24, 2009

It turns out that we’re only 7800 light years away from the black hole in the Cygnus constellation. That’s just over half the distance we had thought it was.

V404 Cygni forms a binary pair with a black hole, a region from which nothing can escape, not even light. Black holes can be detected from the radiation emitted as gas from nearby stars spirals into it.In this case, the black hole is stealing hot gas from its partner V404 Cgyni. An international team of astronomers used the High Sensitivity Array (HSA) telescopes to detect the emitted radio waves every three months for a year.

The cosmologists then used trigonometric parallax to determine the distance to the black hole. This method relies on parallax shift, or the apparent shift in position of an object when viewed from a different vantage point. You can see this for yourself by closing one eye and lining up a finger in front of a distant object. If you switch eyes, the object will have appeared to jump to the side. In this case, the Earth’s movement around the sun provided the different vantage points.

The new distance tells scientists that the black hole formed in a supernova, and that it and its partner star are speeding through space together at 40 km/second.

Wednesday, December 23, 2009

Carbon is a wonderfully utilitarian element, forming an essential part of DNA, protein and many other molecules necessary for life. Diamonds and pencil ‘leads’ are both made of carbon.

Graphene

A particularly interesting form of carbon is called graphene. Graphene is one atom thick, and can be made into narrow ribbons, fullerenes such as nanotubes and Buckyballs (buckminsterfullerenes), and nano-diamonds.

Petr Král’s laboratory at the University of Illinois at Chicago may have discovered a way to shape graphene into even more complex shapes. In computer simulations, they carefully positioned tiny nanodroplets of water along sheets of graphene. Although thewater and graphene do not bind to each other, the van der Waals forces (weak molecular interactions) between them can bend and roll the graphene into a variety of desired shapes. The simulation yielded capsules, knots, sandwiches and rings. There are myriad uses for such structures in medicine, superconductivity and as building blocks of nanodevices.

Buckyball, created by Michael Ströck (mstroeck), February 6, 2006, in iMol for Mac OS X and Photoshop CS2

Tuesday, December 22, 2009

Olympus America Inc. sponsors a photo contest for "the world's most extraordinary microscope images of life science subjects". Next year's deadline is September 30, 2010, in case any of you want to enter.

Orchids are beautiful flowers known for their trickery. Unlike most flowers, which lure their pollinators with nectar rewards, orchids often use deception, producing flowers that look or smell like female insects.

At first glance, this approach seems limiting. After all, nectar will lure a much greater variety of potential pollinators than will a come hither signal which will only lure one species, and only males at that. So why have so many orchids adopted this strategy?

Researchers Salvatore Cozzolino and Giovanni Scopece of the University of Naples Federico II, Steven Johnson of University of KwaZulu-Natal (South Africa) and Florian Schiestl of the University of Zürich have published their conclusions.

If a bee is looking for nectar and pollen, she may visit any number of types of flower. After her first visit, the second flower she visits may also be from a variety of species. The second flower gets no benefit unless the prior flower happened to have been from the same species.

In the case of the orchid, the flowers attract only one type of bee or wasp, a male looking for a mate. When that frustrated bee leaves the first flower, chances are very good that the next flower he selects will be of the same species.

In other words, although fewer overall pollinators may alight on an orchid, those that do will preferentially transfer the right kind of pollen.And ultimately, that’s all the flower cares about.

Monday, December 21, 2009

It has long been known that particular areas in the brain are responsible for specific functions. Damage to Broca’s area impairs your ability to produce language. If it’s the Wernicke region that’s injured, you can’t understand language.

Now Kyrana Tsapkini and Brenda Rapp from Johns Hopkins University have identified a part of the brain responsible for reading and spelling. They studied a patient who suffered from a brain tumor. His treatment consisted of removing a portion of his brain called the leftmid-fusiform gyrus. Prior to the surgery, the patient’s reading and spelling abilities had been normal. Afterwards, however, it was a different story.

Although the patient could still understand spoken language, he had great difficulty in understanding written text and in spelling. This suggests that the portion of the brain that was removed is critical for normal, rapid reading.

Although Ardi was discovered and named in the early 90’s, it took over a decade of research before it was unveiled to the public. Why the long delay? Ardi changed many previously held notions about human evolution. The scientists wanted to be sure of their data before going public. They now have a reasonably complete picture of where and how Ardi lived.

Ardi was a hominid who lived 4.4 million years ago. In comparison, we diverged from chimpanzees about 6 million years ago, and Lucy (Australopithecus afarensis) appeared on the scene 3.2 million years ago. So Ardi is on our branch of the family tree, but not on the chimp branch.

It had been assumed that hominids came down from the trees first, moved onto the savannah, and then began to walk erect. However, Ardi clearly walked upright, based on skeletal features such as its pelvis and limbs, yet it had chimp-like grasping feet. This new data suggests that our hominid ancestors began to walk upright on tree branches, rather than on the ground. The analysis of fossils found near Ardi confirms that it lived in woodland areas, not savannah.

If not to negotiate the newly conquered savannah, why did upright walking evolve? The new theory is that males had to have their arms free to bring presents to females. Unlike the other great apes, but like modern humans, male and female Ardipithecus ramidus did not differ greatly in size. Males probably did not fight each other for control of mates, but instead may have wooed them with food gifts, an enterprise made much easier if you have your hands free.

The study of human evolution is a particular favorite of mine. I think Science made an excellent choice.

Scientists are studying the deepest erupting volcano ever discovered, West Mata Volcano, located 4000 feet down in the Pacific Ocean, in an area bounded by Fiji, Tonga and Samoa.

The volcano was discovered and recorded using ‘Jason’, a remotely operated vehicle (ROV) piloted by Albert Collasius. Using a joystick, he moved Jason to within 10 feet of the eruption where the ROV’s robotic arms could collect rock, water, and biological specimens.

Unexpectedly, the West Mata Volcano is producing boninite lava. This type of lava has only been seen in extinct volcanoes, never before in active ones. It is extremely hot, and the surrounding water is as acidic as battery acid or stomach acid.

Nevertheless, diverse microbes and a type of shrimp were found in the vent water. Genetic tests are underway to determine whether these shrimp are the same species as the specimens collected from seamounts 3,000 miles away.

Because geologists believe that most volcanic activity occurs in the deep ocean, they were very keen to observe a deep sea eruption. Until now, they haven’t been able to catch an eruption in the act.

They hope this new data will provide a better understanding of how the Earth’s crust is recycled and formed on the sea floor.

Friday, December 18, 2009

Zoophysiologist Brian Barnes of the University of Alaska Fairbanks has discovered a new kind of antifreeze in the Alaskan beetleUnder lab tests, the insects survived temperatures of negative 104 degrees Fahrenheit.

Some animals that are adapted to extreme cold make natural antifreezes that prevent their cells from dying. Because living cells are mostly water, at very cold temperatures ice crystals will form within the cells, bursting them. Antifreeze prevents ice from forming, or at least keeps the ice crystals very small when they do form.

Until now, all natural antifreezes have contained protein. However, Upis ceramboides produces a molecule named xylomannan which is composed of a sugar and a fatty acid. Because this new antifreeze molecule is structurally similar to cell wall membrane components, Barnes speculates that it may function as part of the cell wall membrane.

This nontoxic antifreeze could have a number of medical and agricultural uses.

Photo of Upis ceramboides by Todd Sformo/Wildlife biologist, North Slope

Thanks to Cathy Earle and Patty Hunt for catching my wall/membrane error. We all know animals do not have cell walls.

Thursday, December 17, 2009

Alfredo Alexander-Katz in MIT's Department of Materials Science and Engineering and his students have devised a novel way of moving tiny particles.

They set out to mimic the natural system found within organs such as the intestines, in which cilia (tiny filaments) beat in unison, sweeping nutrients along.

To do this, the scientists took tiny beads, each one micron (one millionth of a meter) in diameter, impregnated them with magnets and suspended the beads in a rotating magnetic field. The beads formed into short spinning chains, creating currents that could carry other particles along with them. In some cases, these particles were 100 times larger than the beads, causing Alexander-Katz to nickname the beads ‘micro-ants’.

Today, microfluidics, or the control of tiny amounts of fluid, is used in the manufacture of electronic components. The MIT team hopes that their new method will prove to be a simpler and cheaper alternative for making computer chips, or even targeting medicines to specific locations.

Wednesday, December 16, 2009

There is a long-held assumption that in mammals, female development is the default option. In other words, embryos will develop into females unless certain male factors are present. In particular, an embryo must have the Sry gene, which is located on the Y chromosome present only in males. Females have two X chromosomes, whereas males have an X and a Y.

This still holds true for embryonic development, but a new study led by Mathias Treier at the European Molecular Biology Laboratory (EMBL) shows that the story is different in adults.

They discovered a gene (Foxl2) on a non-sex chromosome (not the X or Y) that is required to keep adult females from becoming males. If this gene is turned off in adult female mice, the male pathway is no longer suppressed and the mouse develops sperm and male hormone-producing cells.

The Foxl2 gene is present in most vertebrates, and thus predates the mammalian Y chromosome. Therefore, there may have been a time when male development was the default option.

Influenza, or the flu, is caused by a group of RNA viruses. These viruses contain up to 8 separate pieces of RNA encoding 11 different proteins. The reason why there is a different flu strain each year is that these individual pieces of RNA, and even sections within the pieces, can be swapped around. In other words, flu viruses have tremendous variability. Antibodies against last year’s flu probably won’t recognize this year’s flu.

Researchers at Rice University and Baylor College of Medicine (BCM) may have found a way around this problem. They studied the hemagglutinin (HA) protein, which is responsible for binding to cells prior to infection. By studying the evolution of H1N1 from its first known appearance in 1918, the team discovered that the portion of HA responsible for actually attaching to cells varies much less than the other sections of the protein. After all, the protein must be able to attach to the cell.

Said Jianpeng Ma, a Rice professor in bioengineering with a joint appointment at BCM:

It becomes a weak link and provides us with a window into the virus that we can monitor. The virus's bottleneck is our opportunity.

The scientists hope that this information will lead to quicker and more reliable vaccines.

By the way, have you ever wondered why this year’s flu strain is called ‘H1N1’? H1 means the virus contains HA protein number one. It also contains neuraminidase (NA) one, hence the N1. There are at least 16 different HA proteins and 10 NA proteins found in influenza.

Tuesday, December 15, 2009

NASA engineer Sotiris Kellas has come up with a device to protect the passengers and pilots in helicopter crashes. The device, called a ‘deployable energy absorber’, is an expandable honeycomb cushion that sits under the belly of the craft, protecting the occupants from the crash.

The device was successfully tested using a MD-500 helicopter and four crash test dummies. Both the helicopter and the dummies were equipped with numerous sensors. Although the results must be analyzed further, the 35 foot drop did not appear to damage the dummies. The same could not be said for the helicopter’s landing gear, though that would be a small price to pay in a real crash.

Monday, December 14, 2009

A single star has turned out be a sextuplet system made of three pairs of binary stars, (pairs of stars that revolve around a common center).

One of the brightest stars in the Big Dipper can be seen by those with good eyesight to actually be a pair of stars. The two stars were named Mizar and Alcor in antiquity.

In 1617, using one of the first telescopes, Benedetto Castelli (a protégé of Galileo’s) discovered that Mizar was in fact a binary pair of stars, now named Mizar A and Mizar B.

In 1890, Mizar A turned out to be a binary pair itself. Almost two decades later, in 1908, Mizar B was also found to be a pair of stars. The entire Mizar/Alcor group became the first-known quintuple star system.

Alcor seemed to be left out of this process until Eric Mamajek from the University of Rochester discovered that Alcor is also really two stars. This discovery was made independently by Ben Oppenheimer of the American Museum of Natural History.

Sunday, December 13, 2009

Skin is our largest organ.Among its many duties is the housing of specific nerve endings that detect temperature, different types of physical sensations (vibrations, pressure, etc.) and pain.

Now Frank Rice of Albany Medical College and his colleagues have discovered a new sensory system located in our blood vessels and sweat glands.

This sensory system was discovered by studying patients with congenital insensitivity to pain.Two such patients were found, who, although lacking all nerve endings normally associated with skin sensation, were still able to detect cold and textures.How was this possible?

The team found sensory nerve endings on the small blood vessels and sweat glands within skin.They hypothesized that under normal conditions, these nerve endings contribute little compared to the more prominent nerves in the skin.However, in cases where there are no such nerves, this sensory system can become perceptible.

The scientists also suspect that this newly discovered sensory system might be involved in mysterious and chronic pain conditions such as fibromyalgia and migraines. If so, treatment plans should account for this possibility.

Saturday, December 12, 2009

Among the recent discoveries about Mars is the large amount of methane in the Martian atmosphere. Methane cannot last long on Mars, and so must be constantly replaced. Most of the methane on Earth is produced by living organisms. Could this mean that there is also life on Mars?

There are several other possibilities for what could be replenishing the Martian methane. One is that the methane is caused by volcanic activity. Unfortunately for this hypothesis, Mars does not seem to have any active volcanoes.

Another possibility is that the methane is renewed by meteorites. As meteorites enter the planet’s atmosphere, they vaporize in a reaction that releases methane. This seemed like the most promising answer until a study was conducted by Richard Court of Imperial College, London.

Using a technique called quantitative pyrolysis Fourier transform infrared spectroscopy, he simulated the effect of falling meteorites in his lab. Combined with the numbers of meteorites falling on Mars, he calculated that meteorites could only account for some 10 kg out of the 100 to 300 metric tons required to maintain the level of methane in the atmosphere.

Two remaining theories are that the methane is released from clathrates (methane trapped within water ice crystals), and of course, that the methane is produced by microorganisms in or below the Martian soil.

One way to determine whether the latter explanation is the correct one is to measure isotope ratios in methane and in water on Mars. Because living organisms preferentially use lighter isotopes, organically produced methane will have a different isotopic ratio than water.

So, does Mars harbor life? In 2011, Nasa will launch Mars Science Laboratory, with a mission to answer these kinds of questions.

View of Mars from Hubble Space Telescope, created by Nasa and ESA, June 26, 2001.

Friday, December 11, 2009

Pneumonia is a common ailment which sickens millions of Americans each year, killing thousands of them. Rapid and accurate diagnosis is essential for proper treatment. Currently, diagnosis can take more than 36 hours, requiring X-rays and bacterial culture of blood or sputum. Misdiagnosis can lead to use of the wrong or no antibiotic, increasing the deadliness of the disease.

Carolyn Slupsky, currently at UC Davis, used a technique called nuclear magnetic resonance (NMR) spectroscopy to find a marker for Streptococcus pneumonia (the most common type of community-acquired pneumonia) in patients’ urine. The test turned out to be so accurate that the patients’ recovery could be charted by following the chemical composition of their urine.

Using the products of the body’s own metabolic processes, or metabolomics, is a promising field of study. Researchers hope that it can be used as a diagnostic tool for a great variety of infections.

Absolute zero, the coldest temperature theoretically possible, is defined as 0 Kelvin and is equivalent to negative 273.15° Celsius or negative 459.67° Fahrenheit. Extremely low temperatures are useful for using and creating superconductors (materials with no electrical resistance or interior magnetic field).

The team used something called ‘spin gradient thermometry’. Simply put, the system to be measured is placed in a magnetic field gradient. The mean magnetization of the atoms can then be used to determine their temperature.

This method has been successfully used to measure temperatures as low as 1 nK. However, scientists are confident that the method could be used for materials as cold as 50 pK, or 50 trillionths of a degree above absolute zero.

Stochastic Scientist? What's up with that?

Why the Stochastic Scientist? As I'm sure you all know, 'stochastic' is another word for 'random', which is what I intend for the focus of this blog. Although my formal training is as a molecular biologist, there are many other fields of science that are also fascinating and beautiful. It's my intention to blog about which ever scientific discovery or invention catches my, and hopefully your, fancy.

I also hope to inspire people to learn more about science. By choosing among a huge variety of scientific endeavors, I'll undoubtably hit upon something that will pique my readers' interest.

I guess I could have called my blog 'The Joy of Science', but that wouldn't have been quite so random.